The invention relates to an endoscope, comprising an elongated shaft and an optical imaging system arranged at a substantially rigid distal end of the shaft for receiving light from an observation area, wherein the optical imaging system is pivotable with respect to the shaft about a first pivot axis which runs about transversely to a longitudinal axis of the shaft.
Endoscopes are used for medical, in particular surgical purposes and for industrial purposes.
In medical procedures, endoscopes are used in minimally-invasive surgery, such as laparoscopic, hysteroscopic, and arthroscopic surgery which is becoming more widely used because it is often less traumatic to the patient. Endoscopes are not only utilized for surgical procedures, but are also utilized as a pure observation instrument for assisting a physician to accurately place medical equipment into a body cavity.
In industrial applications, endoscopes are, for example, used to inspect cavities in machines or machine parts, or they are used to observe dynamic processes in, for example, internal combustion engines.
The present invention is applicable to endoscopes for medical purposes as well as for endoscopes for industrial purposes.
An endoscope enables a person to remotely view an observation area. To this end, an endoscope comprises an optical imaging system arranged at a distal end of the shaft for receiving light from the observation area.
The optical imaging system typically comprises an objective lens arrangement or light entrance window which determines the direction of view of the endoscope. The optical imaging system can further comprise an electronic image pick-up, for example a charged coupled device (CCD) chip, which is also arranged at the distal end of the endoscope shaft proximally to the objective lens arrangement.
Most conventional endoscopes having a rigid shaft provide a limited and fixed direction of view so that in case of a medical endoscope, the surgeon typically must physically reposition the entire endoscope in order to change the endoscopic view within the body cavity, or remove the endoscope entirely and replace it with one having the desired angle of view. Such manipulations and replacements can be undesirable, since they can complicate the surgery and increase the risk of inadvertent damage to body tissue from accidental contact between the tissue and the endoscope.
Therefore, several designs have been proposed to permit individual endoscopes to vary their angles of view without requiring extensive movement of the endoscope. The small sizes of endoscopes, which can be in the order of 3 mm in diameter, place restrictions on such designs, and limit the options available.
An endoscope known from document WO 03/086179A1has an elongated rigid shaft provided at the distal end thereof with an optical imaging system which is supported on a mobile head. The mobile head and, thus, the optical imaging system, is pivotable with respect to the shaft about a pivot axis which runs about transversely to a longitudinal axis of the shaft.
In the 0° position of the mobile head, the direction of view of the optical imaging system lies on the longitudinal axis of the shaft, thus allowing a straight ahead view. In order to change the direction of view, the mobile head can be pivoted about the pivot axis in one plane which includes the longitudinal axis of the shaft.
A drawback of this known endoscope is that the mobile head is pivotable about the pivot axis by an angle of about 90° at most. Thus, this known endoscope is not suited to allow directions of view which are directed backward with respect to the distal end of the endoscope shaft. In order to observe an object in the observation area which is situated behind the distal end of the endoscope shaft, it is, therefore, necessary to draw the endoscope back or to replace the endoscope with an endoscope for backward viewing. As already mentioned, such a displacement or replacement of the endoscope can be undesirable.
Another endoscope having a variable direction of view is disclosed in US 2003/0092966 A1. This known endoscope comprises a rigid shaft having a glass housing mounted at the distal end of the shaft and which is arranged off-axis with respect to the longitudinal axis of the shaft. An optical imaging system is arranged in the housing. By means of a control mechanism having an electrical motor and a gear, the optical imaging system can be rotated about a rotation axis perpendicular to the longitudinal axis of the shaft. While this design renders it possible to adjust a direction of view in 180° (backward) direction with respect to the longitudinal axis, this design has the drawback that the line of sight in 0° direction is offset with respect to the longitudinal axis of the shaft. Such an offset between the line of sight in 0° direction and the longitudinal axis requires a certain habituation to the use of this known endoscope.
Further, U.S. Pat. No. 6,371,909 B1 discloses a variable direction-of-view endoscope. According to one embodiment disclosed in this document, the endoscope comprises an optical imaging system at the distal end of the endoscope shaft, wherein the optical imaging system is pivotable about a pivot axis which runs about transversely to the longitudinal axis of the shaft. Nevertheless, the pivoting movement of the optical imaging system is limited to angles of view in the range from 0° to about ±150°.
There are also known endoscopes having a flexible shaft rather than a rigid shaft. Such flexible endoscopes usually have a control mechanism for bending the distal region of the flexible shaft, and by virtue of the flexibility of the shaft allow angles of view in a plane in the range from 0° to 180°. The control mechanism of such flexible endoscopes, however, consists of a pullwire mechanism which is cost-intensive in terms of manufacture. Further, a conventional flexible endoscope needs space in the distal region when the distal end of the shaft is bended back. This is because the bending radius cannot be made as small as desired due to glass fibers used for the imaging system of such a flexible endoscope.